Quartz lamp mounting



Sept. 29, 1959 F. G. WlLDE QUARTZ LAMP MOUNTING 2 Sheets-Sheet 1 FiledJuly 14, 1955 l1: In.

IN VEN TOR. FREDERICK 6. m1. DE

iiiiiiiiiiiiiiiii ATTORNEY fi 2 Sheets-Sheet 2 F. G. WILDE QUARTZ LAMPMOUNTING Sept. 29, 1959 Filed July 14, 1955 INVEN TOR. FREDERICK 6 W/LDEATTORNEY United States Patent OfiiiC-c 2,906,901 Patented Sept. 29, 19592,906,901 QUARTZ LAMP MOUNTING Frederick G. Wilde, Rochester, N .Y.,assignor to Paragon- Revolute Corporation, Rochester, N.Y., acorporation of New York Application July 14, 1955, Serial No. 521,954 4Claims. (Cl. 313-43 reproduced, is placed upon sensitized paper and fedby belts over a revolving glass contact cylinder in which a lamp unit ismounted, so that the light from the lamp will expose the sensitizedpaper.

The conventional lamp unit comprises a quartz high pressure mercuryvapor lamp, which has an electrode sealed in each end, and a surroundingglass envelope in which the lamp is mounted coaxially. One way ofsupporting the lamp in the envelope is to mount it adjacent each end inmica bafile plates which have central openings which receive the lamptube and whose peripheries engage the inside wall of the envelope. Eachend of the glass envelope is closed by a glass cover having a smallventilating hole in it.

In the past, such lamp units have not performed as satisfactorily asdesired. The mica baifle plates tend to cause a delay in warmup time ofthe lamps. The mica being cold tends to keep the electrodes from warmingup. This delays the start of useful operation of the machine. With priorlamp mountings, moreover, the free circulation of air through theenvelope is prevented. As a result, the lamp, operating under highvoltage, frequently becomes overheated with long use and, in time,crystallization of the lamp tube takes place, causing pitting of thetube, which breaks the vacuum and terminates the life of the lamp.

In addition, it has been difficult to assemble prior lamp units inthefield because the mica supports, for 2 1, instance, have to bepositioned about the lamp tube and seated securely against the innerwall of the envelope. It has been the practice therefore to ship thelamps assembled in their glass envelopes. This increases the shippingbulk which means increased shipping costs, and also increases the dangerof breakage.

One object of this invention is to provide a lamp unit for printmakingmachines which can be quickly and easily assembled in the field, andwhich can, therefore, be shipped disassembled.

Another object of the invention is to provide a lamp assembly formachines of the character described which will make it possible to shiplamps separate from envelopes, and which will make it simple for a manin the field to install a lamp in a machine. 7

Another object of this invention is to provide alamp assembly of thecharacter described which will permit of a substantially shorter warmuptime than conventional lamp units.

Another object of this invention is to provide a l assembly soconstructed as to increase lamp life.

A further object of this invention is to provide a lamp assembly soconstructed that the heat generated by the lamp can be continuouslydrawn away from the lamp, .thereby preventing deterioration and pittingof the lamp tube. v Another object of this invention is to provide alamp assembly which is so constructed that air can readily be circulatedover the lamp to keep it from heating up excessively.

Still further objectsof this invention are to provide a lamp assembly ofsimplified-but rugged construction which will permit readily changinglamps without having to change envelopes.

Other objects of the invention will be apparent herea inafter from thespecification and from the recital of the appended claims.

In' the drawings:

Fig. 1 is a fragmentary axial section of a lamp assembly constructedaccording to one embodiment of this invention;

Fig. 2 is a section taken on line 22 of Fig. 1 look ing in the directionof the arrows; I

Fig.3 is a front view on a greatly reduced scale of a print-makingmachine showing diagrammatically the manner of mounting this lampassembly in the machine and the means for circulating air through theenvelope to cool the lamp; 7

Fig. 4, is a fragmentary axial section of a lamp assembly, constructedaccording to another embodiment of this invention, and showing more orless diagrammatically the mounting of this assembly and the air ductconnections thereto; I I f Fig. 5 is a transverse section on the line 55of Fig. 4 looking in the direction of the arrows;

Fig. 6 is a front view on a very 'much reduced scale of the print-makingmachine and illustrating, in particular, how the lamp assembly isconnected to the blowers of the machine for cooling the lamp and itsenvelope; and. t 1

Fig. 7 is a side view of the machine, a portion .being broken away, toshow one openfend of the lamp assembly, the blowers and theirconnections.

Referring now to the drawings bynumerals of reference, and first to theembodiment shownin Figs. 1-3 inclusive, 20 indicates generally the lampunit. This lamp unit comprises a quartz, high-pressure, mercury vaporlamp which is in the form of a cylindrical tube 21' closed at each endby an end member 22'. These end members are of slightly smaller diameterthan tube 21 thereby forming a shoulder 23 adjacent each end of thetube.

Extending outwardly of each end member 22 is a vacuum seal 24 having .alead wire (not shown) passing axially through it which connects to anelectrode, projecting inside the tube 21, Each electrode is connected toan insulated conductor 25 which is in turn connected to a source of highvoltage electrical power through a conductor rod 26 incased in'insulating beads 27.

Tube 21 is supported coaxially within a cylindrical envelope 30 which isopen at both ends and which is made of a glass generally unaffected byheat, chemicals, or electricity, such as Pyrex glass. The tube issupported in the envelope by a pair of resilient, spider-like supports31 which engage the peripheries of end members 22 of the lamp and whichseat against the shoulders 23. Each support 31 comprises four resilientstraps 29 which are brazed or soldered together at their inner ends toform a hollow square, and which are reversely bent at their outer ends,as denoted at 32. The hollow square formed by each set of straps isadapted to receive and resiliently grip an end member 22 and hold itSecurely. The reversely bent portions 32 of the straps provide springportions which resiliently engage the inside wall of the envelope 30.Thus the supports 31 serve to resiliently but securely support the lamptube 21 in the envelope 30.

The ends of envelope 30 flare outwardly somewhat, as shown; and, one end34 of the envelope is closed by a glass cover 35. Cover 35 has anelongate neck portion 36 which fits into envelope 30 and which engagesat its inner end against the outer face of the support 31 which isadjacent that end of the envelope. 1

Cover 35 is held in place by a split ring 37which embraces the flaredend 34 of the envelope. This ring is provided with diametrically-locatedears 38, to each of which there is secured by a screw 39 one end of acoil spring 40. The other end of each of these springs 40 is connectedto a strap 41 that engages over the outer end of cover 35.

The opposite end 42 of envelope 30 is open, but a glass sleeve 45 isinserted in this open end. This sleeve has an outer flared end and anelongate neck portion 46 similar to neck 36. Neck portion 46 at itsinner end engages the spider-like support 31 which is adjacent end 42 ofthe envelope, thereby holding this support against the cooperativeshoulder 23 on the tube 21. For clearness of illustration the spacebetween neck portion 46 and the inside wall of end 42 of envelope 30 isshown exaggerated in Fig. 1. Actually there is considerable surfacecontact between the parts 46 and 42, and sleeve 45 may be held in place,therefore, solely by friction. The envelope is secured in place byconventional hangers 43 which are fastened in conventional manner byscrews 44 to the holders (not shown) which support the lamp unit insidethe contact cylinder of the machine.

Cover 35 and sleeve 45 are provided with holes or outlets 47 and 48,respectively, through which the conductor rods 26 and insulating beads27 pass. Cover 35 is also provided with a small aperture 49 which servesas an inlet for air.

In use, the lamp unit is mounted within a conventional glass contactcylinder, over which the sensitized paper is drawn to expose it. 50indicates the machine generally, and 51 denotes the glass contactcylinder and its support. The cylinder is mounted in conventional mannerto revolve in the machine around the lamp unit 20. Both ends of thecontact cylinder are open.

In order to prevent overheating of tube 21 when the lamp is mounted in aprint-making machine and is in operation, a system for circulating airabout the lamp is provided, as shown in Fig. 3.

Print-making machines of the type, to which this invention applies, arecustomarily provided with suctionactuated separators or tanks forseparating the prints from the tracings after prints have been made. Theair pump employed for operating these suction-actuated separators canalso be used for operating the air-cooling system for the lamp. Thus,the end of the contact cylinder support, to which the open end of sleeve45 is adacent, may be connected by a conduit 52 with the air suctionpump 54. As the pump operates, then, air is drawn through the left handopen end of the contact cylinder 51, the hole 49 in the envelope cover35, around and about the lamp 21 for the full length of the lamp andthrough duct 52 to pump 54. The suction exerted on the open end ofsleeve 45 will pull the air out of the envelope 30. The path of travelof the cooling air is denoted by the arrows in Fig. 3. Pump 54 may beconnected to a ventilating stack, not shown, through which the air fromaround the lamp and hot air and ammonia vapors can be expelled from themachine into the outside atmosphere. The air entering the envelope comesfrom the room in which the machine is located, entering the machinethrough clearances between the frame members at the side of the machineor through any other gaps or openings.

Such air movement through envelope 30 is impossible with quartz lampunits employing mica bafile plates for supporting the quartz tube,because the bafile plates bar free passage of air. With the spider-likesupports 31, the air can flow readily through the envelope 30 and aboutand along the lamp.

The hole 49 in cover 35 is of small, predetermined size so as to limitthe rate at which air may be sucked into envelope 30. By thuscontrolling the volume of air passing through envelope 30, excesscooling of lamp tube 21 is prevented. If a large hole was employed, orno closure 35 was used at all, too great a volume of air would be drawnthrough the envelope and overcool the tube. Overcooling would reduce thepressure of the mercury within the tube and cause a loss of light outputand decreased light intensity.

Controlled-cooling of lamp tube 21 gives it a longer life by eliminatingthe possibility of overheating with resulting crystallization andpitting. In turn, tube 21 does not heat the glass contact cylinder 51 inwhich it is mounted as much as it otherwise would. Thus, a lower surfacetemperature of contact cylinder 51 is obtained which is highly desirablebecause smoother transmission of tracings and sensitized paper throughthe machine results. This is because there is less likelihood of thepapers sticking to the glass contact cylinder, when the revolvingcylinder is cool.

Another advantage of the structure described is that by drawing airthrough envelope 30, ozone, which is produced around the quartz lamp, isremoved. Thus, the presence of an objectionable ozone odor around themachine is obviated.

The elimination of the bafile plates also greatly decreases the warm-uptime for the unit. It has been found that a unit 20 constructedaccording to this invention warms up and is ready for print-exposing inless than two minutes after the lamp switch is snapped on, compared tothe seven minutes or more required of units supported by mountings ofprior design. Further, the simpler construction of unit 20, makes .itpossible to ship the lamp separate from the envelope. This makes iteasier to pack lamps against breakage in transportation; and the wholeunit can be easily and quickly assembled at its destination with littleor no danger of any of the parts being broken.

Figs. 47 show a modified lamp mounting. In this mounting a stream of airis passed over the periphery of the envelope, instead of being passedthrough the envelope as in the previously described embodiment of theinvention. The envelope, which is denoted at 30a, may be of the samegeneral construction as envelope 30. The envelope 30a is shown in Fig. 4with the ends partly broken away.

The lamp tube 21 is of conventional construction and is connected inconventional manner to the source of electrical power. The lamp tubeconstruction may be like that previously described. The lamp tube may besupported in the envelope 30a by spider-like supports 31 similar tothose previously described. The ends of the envelope 30a have glasssleeves 45 inserted in them, similar to sleeve 45 previously described.Both ends of envelope 30a are, therefore, left open. The whole lampunit, comprising lamp and envelope, is mounted, as in the previouslydescribed embodiment of the invention, inside the rotary glass contactcylinder and its support, here denoted at 75.

For cooling the lamp tube in this embodiment of the invention, however,air is pulled over and around the envelope 30a for the full lengththereof. For this purpose, there is a generally crescent-shaped duct 74mounted within the contact cylinder 75. Openings 76 and 77 are providedin opposite side walls 78 and 79 of the frame of the machine in registrywith the contact cylinder 75 and its support, and drums 8 1, which aresecured to the side walls 78, 79,, respectively, enclose openings 76:and 7 1, @respectively. Duct 74 is closed at both ends, but

has a (plurality of elongate slits 80 extending longitudinally of it andopening into contact "cylinder 75. The contact cylinder is supported inconventional manner by conventional journals from the walls 78 and 79and the inner ends of the drums 81 are secured to these walls about-theopenings 76 and '77, respectively, in air-tight relation thereto and tothe contact cylinder 75. Opposite ends of duct 74 are connected bytubular conduits 82, with a blower 54a which is mounted in the base ofthe machine 85. The drums 81 are closed at their outer ends and areconnected by tubular conduits 86 with a second blower 54b also mountedin the base of the machine.

The ends of the envelope 30a and the sleeves 45 project outwardlythrough the outside walls 88 of the drums 81.

The blower 54a is connected to crescent-shaped duct 74 so that air isdrawn in from the outside and is driven through conduits 82 into duct 74and through the slits 80 therein into contact cylinder 75, and aroundand along the periphery of envelope 30a; and the blower 54b is connectedto drums 81, so that the air flowing into the contact cylinder 75through slits 80 in duct 74 Will be drawn from the cylinder 75 throughdrums 81 and ducts 86 and exhausted to the outside atmosphere by theblower 54b. Thus, air will be circulated around envelope 30a to coollamp 21. Since the open ends of envelope 30a are outside of theair-circulating system, the quartz lamp tube 21 Within the envelope isnot subjected directly to the forced-draft of cooling air. However, thelamp tube is cooled indirectly by the cooling of envelope 30a whichsurrounds it. Moreover, since the ends of the envelope are open, air canflow through the envelope; and heat inside the envelope will, therefore,be dissipated without lowering the lamp temperature to any undesirabledegree.

To protect the machine operator from the lamp if for some reason be orshe opens one of the side doors of the machine while it is in operation,metal flaps 90 are provided to register with the opposite ends of theenvelope 30a. These flaps are hingedly connected to brackets 91, thatare supported from drums 81, and may be swung upwardly when the lamp isnot in use to allow ready access to the lamp.

The results obtained through this embodiment of the invention aresimilar to those achieved with the embodi ment of the invention shown inFigs. 1-3. An important advantage of both embodiments is that tube 21 isprevented from overheating and thus has a much longer operating life.Further, the use of supports 31, instead of mica bafiie plates, tosupport the quartz lamp tube inside of the envelope, reduces lampwarm-up time, permits quick assembly of the lamp unit, makes assembly ofthe unit by men in the field much easier, lowers shipping costs, andreduces the likelihood of parts breakage.

While the invention has been described in connection with two differentembodiments thereof, it will be understood that it is capable of furthermodification, and this application is intended to cover any variations,uses or adaptations of the invention following, in general, theprinciples of the invention and including such departures from thepresent disclosure as come within known or customary practice in the artto which the invention pertains, and as fall within the scope of theinvention or the limits of the appended claims.

Having thus described my invention what I claim is:

1. In a machine for making reproductions on lightsensitive sheets, anelongate, tubular lamp, a transparent envelope surrounding said lamp,means for supporting said lamp in said envelope in radially-spacedrelation to said envelope, a transparent, rotary, tubular contactcylinder surroundingsaid envelope in radially-spaced relation thereto, aduct within said cylinder, means connecting said duct witha source ofair under pressure, said duct having ope'ning's. extending axially andcircumferentially of said envelope to deliver-the along and around saidenvelope, said duct-projecting beyond opposite ends of said cylinder, asecond duct system, said second duct system enclosing the first-namedduct and having airtight connection w'ithtsaid cylinder at opposite endsthereof, suction means for withdrawing airfrom said cylinder, and meansconnecting the second duct system with suction means to suck air fromsaid cylinder, said envelope projecting at opposite ends beyond andthrough the second duct system and being open at its opposite ends, saidenvelope being open at both ends to atmosphere, whereby outside air maycirculate by convection through said envelope lwhile air is beingpositively circulated about and along said envelope.

2. In a machine for making reproductions on lightsensitive sheets, anelongate, tubular lamp, a transparent, generally cylindrical envelopesurrounding said lamp, means for supporting said lamp in said envelopein radially-spaced relation to said envelope, a transparent, rotary,tubular contact cylinder surrounding said envelope in radially-spacedrelation thereto, a conduit in said cylinder extending axially of saidenvelope and having air discharge openings therein that extend axiallyand circumferentially of said envelope, said conduit being closed exceptfor said openings, means for connecting said conduit with a source ofair under pressure, and separate means for withdrawing air from saidcylinder, the opposite ends of said envelope being open and protrudingbeyond said cylinder, whereby outside air may circulate by convectionthrough said envelope while air is being positively circulated about andalong said envelope.

3. In a machine for making reproductions on lightsensitive sheets, anelongate, tubular lamp, a transparent envelope surrounding said lamp,means for supporting said lamp in said envelope in radially-spacedrelation to said envelope, a transparent, rotary, tubular contactcylinder surrounding said envelope in radially-spaced relation thereto,ducts registering with said cylinder and having air-tight connectiontherewith and closing opposite ends, respectively, thereof, saidenvelope projecting at opposite ends through said ducts and being openat said opposite ends, a conduit in said cylinder extending axially ofsaid envelope and having air discharge openings therein that extendaxially and circumferentially of said envelope, means for connectingsaid conduit with a source of air under pressure, and means forconnecting said ducts to suction means for withdrawing air from saidcylinder, whereby air may circulate by convection through said envelopewhile air is being positively circulated about and along said envelopeand said cylinder. 7

4. In a machine for making reproductions on lightsensitive sheets, anelongate lamp tube, a transparent envelope surrounding said lamp tubefor the full length thereof, resilient means for resiliently supportingsaid lamp in radially spaced relation to said envelope, said lamp tubehaving shoulders formed adjacent opposite ends by reduced diameterportions thereof, said resilient sup-' porting means having openingstherethrough for the passage of air along said lamp tube and comprisinga pair of spiders seated against said shoulders respectively, eachspider comprising a plurality of resilient straps connected together attheir inner ends to form a central opening for receiving and resilientlygripping said lamp tube, each of said straps having a reversely bentportion at its outer end that resiliently engages the inside of saidenvelope, two transparent holders having neck portions inserted inopposite ends of said transparent envelope frictionally to engage theinside Wall of said envelope and abutting against said spidersrespectively, one of said holders being in the form of a sleeve andbeing open at its outer end, and the other of said holders constitutinga closure for 7 one end of said envelope but having a small diameterReferences Cited in the file of this patent hole through it to permitlimited circulation of air through UNITED STATES PATENTS the envelope, atransparent, rotary, tubular contact cylinder surrounding said envelopein radially-spaced rela-' 2168861 Blackburn 1939 tion thereto, the openend of said sleeve extending beyond 5 22951031 Davls "-1 Sept' 1942 thecorresponding end of saidcontact cylinder, and a '23791488 Koch et a11943 duct connecting suction means in air-tight relation with 2'3867331945 said corresponding end of said contact cylinder, said con- BoddleJune 1949 tact cylinder being open at its opposite end, whereby airFOREIGN PATENTS can be drawn into said envelope through said hole and 10692 843 through said contact cylinder, Great Bntam June 1953

